A cohort of chimpanzees was infected with various HIV-1 isolates in the years 1984-86. After a 10 year asymptomatic period, one ape developed anemia, CD4+ T cell loss and opportunistic infections similar to human AIDS. A second animal transfused with blood from the "sick" chimpanzee was shown to suffer a dramatic CD4+ T cell loss post transfusion. A number of additional animals infected with LAV in this cohort appear to experience progressive CD4+ T cell loss as well. Since sequential blood samples had been collected and stored during most of the "clinically asymptomatic" period, our goal was to attempt to delineate immune parameters that accompany/predict the clinical demise in these animals. Further, we attempted to define the hematological abnormalities induced by this selected variant of HIV-1 that leads to nonregenerative anemia and finally death. Results obtained on the first 2 animals have been presented at the 14th Symposium on Nonhuman Primate Models for AIDS a nd are being published as a manuscript in the Journal of Medical Primatology.